Get moving: Guidelines set healthy activity levels

October 10, 2008 11:16:07 AM PDT

By LAURAN NEERGAARD

WASHINGTON - October 7, 2008 - --

Get moving: New exercise guidelines released Tuesday set a minimum sweat allotment for good health. For most adults, that's 2½ hours a week. How much physical activity you need depends largely on age and level of fitness.

Moderate exercise adds up for sluggish adults. Rake leaves, take a quick walk around the block or suit up for the neighborhood softball game. More fit adults could pack in their week's requirement in 75 minutes with vigorous exercise, such as jogging, hiking uphill, a bike race or speedy laps in the pool.

Children and teens need more - brisk activities for at least an hour a day, the guidelines conclude.

Consider it the exercise version of the food pyramid. The guidelines, from the Health and Human Services Department, aim to end years of confusion about how much physical activity is enough, while making clear that there are lots of ways to achieve it.

"For a total couch potato who does zero, zip, nada, getting up and walking 10 minutes a day is a great start," said Rear Adm. Penelope Royall, deputy assistant secretary for disease prevention.

But people need to work toward eventually hitting that weekly minimum, she added. "Some is better than nothing, and more is better."

The guidelines come as scientists are trying to spread the word to a nation of couch potatoes that how active you are may be the most important indicator of good health. Yet a quarter of U.S. adults aren't active at all in their leisure time, government research concludes. More than half don't get enough of the kind of physical activity that actually helps health - walking fast enough to raise your heart rate, not just meandering, for instance. More than 60 million adults are obese.

Worse, the nation is raising a generation of children who may be less healthy than their parents. About a third are overweight and 16 percent are obese. And while young children are naturally active given the chance, schools are decreasing the amount of recess and gym time. By high school, a recent study found, fewer than a third of teens are getting an hour of activity a day.

To put science behind the how-much-is-enough debate, HHS gathered an expert panel to review all the data. The panel found that regular physical activity can cut the risk of heart attacks and stroke by at least 20 percent, reduce chances of early death, and help people avoid high blood pressure, type 2 diabetes, colon and breast cancer, fractures from age-weakening bones and depression.

The government used that scientific report to set the minimum activity levels.

"The evidence is clear," Leavitt said Tuesday in announcing the guidelines. "The more physically active you are, the more health benefits you gain."

The kind of exercise matters a lot, said Dr. William Kraus, a Duke University cardiologist who co-authored the scientific report. Runners like Kraus can achieve the same health benefit in a fraction of the time of a walker.

"If you do it more intense, you can do less time," explained Kraus, who praised the guidelines for offering that flexibility. "This brings it back down to earth for a lot of people."

What's the right kind of exercise? The guidelines advise:

-You don't have get all the activity at once. A walk for an hour three days a week works as well as, say, a 30-minute exercise class on weekdays or saving most of the activity for a two-hour Saturday bike ride.

-For aerobic activities, go at least 10 minutes at a time to build heart rate enough to count.

-You should be able to talk while doing moderate activities but not catch enough breath to sing. With vigorous activities, you can say only a few words without stopping to catch a breath.